What colour was the mounting base and arm for the rear view mirror in a 79 W150? Was it the same as a 78? The one in my truck is silver but LMC shows it as black.
Also how wide were they? LMC shows 8", 10" and 12".

 

I think it depends on what vendor supplied the part. I vaguely remember some silver ones but the ones I've installed were all black. However, considering how many vehicles I've worked on over the years, there's no telling. I'd see what I could find in a bone yard.